Mammographic biopsy needle holder system

ABSTRACT

An X-ray mammographic biopsy needle holder positioning system wherein the X-ray source is tilted to provide parallax views of the needle holder inserted in the breast. The tilting occurs independently of the breast compressor which remains untilted.

FIELD OF THE INVENTION

This invention is concerned with radiogaphic imaging systems and moreparticularly with such systems used to assist in locating growths forthe surgeon in mammallary biopsy procedures.

BACKGROUND OF THE INVENTION

X-rays have long been used to acquire images of the internal functioningof the patient's body for diagnostic purposes. More recently X-rayequipment has been used for assisting in invasive techniques such asbiopsies and lithotripsy. For example, in X-ray mammography the breastof the patient is X-rayed and X-ray films are closely viewed todetermine whether there are any microcalcification or other growths(hereinafter generally termed "lesions".) If a lesion is discovered thenit is necessary to determine if it is a benign growth or if it requiresimmediate treatment. For such a determination is it often necessary toperform a biopsy to finally determine whether the lesion discovered inthe X-ray image is pathological or benign. The radiologist performs aneedle localization procedure whereby he inserts a radio opaque needleinto the center of the susceptor growth to indicate to the surgeon thetissue to be excised. More particularly, the patient is brought to themammographic system. The breast is compressed between horizontal platesattached to the X-ray equipment C-arm. The C-arm is a "C" shaped bracketwhich normally holds the X-ray tube at the top and the X-ray beamreceptor at the bottom. The raiologist marks the breast or one of thecompression plates at a point in a plane where he thinks the lesion islocated, based on the study of the preliminary X-ray. An X-ray image istaken and developed to determine whether the marking is indeed in thecorrect location. If it is not in the correct location, then theradiologist repeats the marking procedure, acquiring another X-rayimage. When the marking is indeed aligned with a lesion, the radiologistinserts the holder of the lesion-locating needle into the compressedbreast through an aperture or recess in the compression plate at themarked point so as to center the holder tip within the lesion that wasobserved in the preliminary X-ray.

The breast is then removed from the compression plates and the C-arm isrotated 90 degrees, the breast is again compressed but now thecompression plates are vertically aligned. Another X-ray is acquired tocheck the alignment of the needle holder tip and the lesion in thehorizontal plane to assure that the holder tip is indeed within thelesion. If the holder tip is not within the lesion, or sufficientlyclose, the needle holder is moved and another image is acquired. Theprocess is repeated until coincidence is obtained. Then the needle isinserted into the holder and the holder is withdrawn.

Thus in the prior art X-ray mammography a plurality of X-ray images anda plurality of breast clamping operations are required to position theneedle holder to locate the lesion for the surgeon. The repeatedoperations are time consuming and uncomfortable for the patient andsubject the patient to the X-ray dosage required to acquire the manyimages over a substantial area of the breast.

Radiologists and scientists have been seeking to improve the biopsyneedle-positioning procedure. For example, the positioning procedureoutlined hereinabove applies when the lesion can be seen in twoorthogonal views. Sometimes the lesion can only be seen in one view. InMarch of 1984 a presentation at the National Conference on Breast Cancerof the American College of Radiation described a technique for amammographic needle localization of lesions which cannot be imaged intwo orthogonal views, but only in one of them. In this technique theX-ray beam is moved 30 degrees in a xeromammographic system where thereis no breast clamping. An article describing the presentation appearedin the American Journal of Radiology Vol 144, pp 911-916, May 1985. Thearticle describes a method that does not use C-arm clamping, and whereby it is possible to locate the needle using images taken at twopositions at 30 degrees apart.

Mammographic compression devices for normal X-ray film mammographicsystems originally started with what may be described as dependentcompression. At the top of the C-arm there was an X-ray tube andcollimator arrangement which served as the source of the beam. A coneextended from the soruce to the breast to compress the breast againstthe X-ray radiation receptor or film at the bottom of C-arm. Thus thecompression means i.e. the cone was fixedly attached to the C-arm. Themovable film container provided the other side of the compression means.Rotating the C-arm also rotated the compression means.

Subsequently, movable compression plates were attached to the C-armbetween the X-ray source at the top of the C-arm and the X-ray receptor(i.e. the film) at the other end. The movable compression plates weremovably attached along the longitudinal axis of the C-arm to adjust tothe woman's breast. In this arrangement the compression plates rotatewith the C-arm. Thus, this arrangement also requires unclamping andreclamping the breast when the C-arm is rotated, even through smallangles.

Compression plates are important in mammography to improve the qualityof the image and to thereby enable the discovery of more lesions. Whenthe breast is compressed it flattens and absorbs the X-ray beam less,and more uniformly. In addition extraneous movements are eliminated.These beneficial results of clamping improve the quality of the image.Therefore, it is highly desirable to compress the breast formammographic breast image processing.

From the above description of the prior art it is readily understoodthat it would save time and reduce patient discomfort if a system couldbe provided that generates an immediate image to aid in positioning thelesion-locating needle holder for biopsy purposes. It would save furthertime and discomfort if it could utilize a single clamping position, andavoid movements of the lesion during reclamping with consequent relativemovement of needle holder and lesion.

Until now, imaging chains have not been used for invasive mammographictechniques such as for positioning the biopsy locating needle. Until nowthe prior art systems using breast compression means have rotated theX-ray beam through 90 degrees for ascertaining that the needle holdertip is indeed within the lesion. The prior art systems have used anX-ray film means for acquiring images. When films are used as the X-rayreceptor, waiting periods for the developing of the films are requiredbefore the radiologist can proceed with the next step in properlypositioning the needle.

Accordingly, it is an object of the invention to provide mammographicbiopsy needle positioning system using a radiographic imaging chain forproviding the image which indicates the location of the needle holder.

It is also an object of the invention to provide in a system forpositioning a biopsy needle locator in an X-ray mammographic systemmeans for tilting the X-ray beam to obtain a parallax view of the needleholder and the breast without having to move the breast compressionmeans when moving the beam. The system is designed to locate the biopsyneedle in a minimum of time with a minimum of X-ray dosage and a maximumof accuracy.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the present invention a mammographic biopsy needleholder positioning system is provided, said system comprising:

X-ray tube means for generating X-ray beams directed to pass through thebreast of a patient,

collimating means for limiting the X-rays passing through the breast tosmall areas,

breast compression means for compressing the breast in a direction todecrease and make uniform the path length in the breast through whichthe X-ray beams pass,

X-ray receptor means on the side of the breast opposite the X-raysource,

means for tilting said X-ray source a sufficient amount to obtain aparallex view of the biopsy needle holder inserted into the breast, and

said compression means being uncoupled from said means for tilting saidX-ray source.

A feature of said compression means is that they are adjustably mountedrelative to the X-ray beam to enable centering the suspected lesion onthe x-ray beam axis without the need to release the breast compression.

Also in accordance to the present invention a mammographic biopsy needleholder locating system is provided, said system comprising:

X-ray source means for generating X-rays directed to pass through thebreast of a patient,

collimator means for limiting the X-rays passing through the breast tosmall areas,

means for compressng the breast substantially in the direction of theX-ray beams,

means for tilting the X-ray source for obtaining images of the breastfrom more than one angle,

X-ray receptor means located on the side of the breast opposite theX-ray source, and

said X-ray receptor means comprising an X-ray imaging chain.

A feature of the invention comprises the use of high resolution means insaid imaging chain. Thus said imaging chain comprises a high resolution,small diameter, fluorescent screen and means for optically placing saidfluorescent screen in the path of the X-rays which have passed throughthe breast; a high resolution image intensifier; a high resolution TVcamera for providing video signals responsive to the output of the imageintensifier which operates responsive to the signals from thefluoroscent screen.

The imaging chain enables instantaneous views of the needle or theneedle holder as it is inserted into the breast. This eliminates thenecessity of the X-ray film, among other things, and the time requiredfor its chemical development.

A feature of the invention includes optically coupling said imageintensifier to said fluoroscent screen over a folded optical path.

A related feature of the present invention comprises reflecting means(for coupling between the fluorescent screen and the image intensifier)mounted juxtaposed to the junction area between the breast and the chestwall; thereby enabling imaging of an area not otherwise obtainable usingimaging chain equipment.

Another feature of the invention comprises optically coupling saidimages intensifier to said video camera through a beam splitter.

Yet another feature of the invention comprises an analog-to-digitalconversion means coupled to a frame grabber or frame store means andenabling presentation of the image acquired during X-ray exposure afterthe exposure has been completed.

Yet another feature of the invention reduces the radiation dosage byusing an unique incremental dosage system which averages the accumulatedsignal strength per repeated exposure until a desired image quality isacquired.

Still another feature of the invention comprises the use of stereoimaging means for acquiring a stereo image of the breast during thebiopsy needle holder positioning process to thereby enhance the abilityof the doctor to obtain a biopsy specimen from the desired section ofthe breast and to reduce the time required for the process.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of the presentinvention will be best understood when considered in the light of thefollowing description made in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is a block diagram of a mammographic fluoro-biopsy needle holderpositioning system;

FIG. 2 is a block diagram of another embodiment of the system of FIG. 1;

FIG. 3a shows decoupled, independent breast compression plates for usewith small angle biopsy needle holder positioning systems;

FIG. 3b shows an angled biopsy needle holder insertion device;

FIG. 4 shows an arrangement for adjustably moving the breast compressionmeans in the horizontal plane;

FIG. 5 is a block diagram of the inventive system showing theincremental dosage means; and

FIG. 6 is a diagram of a system using stereo in the embdiment of FIG. 1.

GENERAL DESCRIPTION

The mammographic imaging chain system 11 of FIG. 1 includes an X-raytube means 12. Preferably it is a micro-focused type X-ray tube. Thetube includes an X-ray target 13, to which the X-rays are directed fortransmission through an X-ray collimator 14. The collimator has anaperture 16 therein; relatively a small size can be used since the beammerely has to encompass the lesion and a small area there about. Thesmall size improves image quality by minimizing scatter, for example; italso reduces the dose.

The patient's breast is shown as 17 located between two compressionplates 18a and 18b. On the side opposite to the collimator side of thebreast is a fluorescent screen 19. The fluorescent screen detects X-rayradiation passing through the breast and responsive to the detectedX-ray photons releases light photons.

Means are provided for coupling the fluorescent screen to an imageintensifier. More particularly the light photons are focused by lens 21onto an optical image intensifier 22. The optical image intensifier iscommercially available and has a luminance gain of 100 to 100,000. Thespecific model shown is an AEG XX 1066 and in the preferred embodimenthas a fibre optic input 23. Electron lenses direct the image onto anelectrode 24 associated with a fluorescent screen.

Between the fibre optic input 23 and the output electrode 24 are a pairof lens electrodes 26 and 27 used to direct and focus the image onto theoutput screen. The output of the intensifier 24 may be optically coupledto a video camera 28 through an image distributor 29. It should beunderstood that other means may be provided such as direct coupling ofvideo camera and the image intensifier. This distributor includes acollimator lens 31 and a 90% partial reflector 32. The reflector splitsthe image between an eyepiece 33 and a TV camera lens 34. The eyepieceimage is viewable by the clinician or doctor depicted as 36. The outputof the video camera 28 is directed to a monitor 37. Thus the image maybe viewed directly through the image distributor or displayed on themonitor.

A biopsy needle holder 38 is shown inserted into the breast and alignedwith a lesion in a plane normal to the pressure plates. However, itcould be aligned with, in front of or behind the lesion in the plane ofthe lesion parallel to the compression plates. FIG. 1 shows afluoroscopically assisted biopsy needle holder positioning systemcomprising a small field of view as determined by the aperture of thecollimator. The small field of view enables using a low dose andsuffering very low scatter. Note that in FIG. 1 the fluorescent screenmay be juxtaposed to the image intensifier input fiber optics, if it isin optical contact therewith.

When the lesion being examined is at the junction of the beast and thechest wall, there is no room for the fluorescent screen to be placed toobtain an image of the lesion. The situation is remedied in theembodiment shown in FIG. 2. More particularly FIG. 2 at 41 shows afluoroscopically-assisted mammographic biopsy system; including an X-raytube 42 mounted on one side of the collimator 43. The collimator has anaperture 44 therein which limits the field of view or the area uponwhich the X-rays impinge. The breast of the patient 46 is shown locatedbetween a pair of compression plates 47a and 47b.

Means are provided for collecting photons even in the area of the breastclose to the chest wall. More particularly, a fluorescent screen 48 isshown mounted juxtposed to the breast and normal to the chest wall. Someof the light photons emitted from the fluorescent screen fall upon amirror or prism 49 optically coupled to the image intensifier 51 throughan optical lens system shown at 52. The image intensifier preferably isa one-inch type, high-resolution intensifier e.g. 320 line pairs percentimeter. Of course, a similar system in which the lens 52 is placedbetween the fluorescent screen 48 and the mirror 49 may sometimes beadvantageously used. While the mirror or prism 49 is shown, thefluorescent screen output could be coupled to the image intensifierthrough fiber optic means.

The output of the image intensifier is optically coupled to a highresolution video camera 53 through a lens system 54. The lens system mayinclude an image splitter such as that shown in FIG. 1; however, theimage splitter is not necessary to the invention. The video camera 53 iscoupled to a display monitor 56. Image processing means may be providedwhich process the data to provide the image. The processing meanspreferably include a frame grabber frame holder or frame memory means.

The biopsy needle holder arrangement is shown in FIG. 2 in schematicfashion at 57. The needle holder as shown may be moved to be insertedanywhere in the horizontal plane. Thus, it can be positioned so as to beinserted into lesion wherever it is. The folding mirror 49 enablesobtaining the light photons from the fluorescent screen even when thelesion is near the chest wall. The difficulty of obtaining proper imagesnear the chest wall is especially great when the images arefluoroscopically obtained and where the output of the screen has to bedirected to an intensifier. Even when a small intensifier is used thediameter of the intensifier itself limits images that can be obtainedfrom lesions that are close to the chest wall.

FIG. 3a shows a decoupled independent compression means, moreparticularly the C-arm, assembly 61. At one end of the C-arm the sourceof the X-ray beam is shown as X-ray tube 62 and collimator means 63. Thecollimator means is used in this invention to limit the area of thebreast upon which the X-ray beam impinges. It is possible to limit thearea in this system since the radiologist is only interested in imagingan area around lesions that are to be recepient of the needle. The C-arm61 tilts about a pivoting axis shown at 66, i.e. it pivots around anaxis that is normal to the plane of the paper on which the drawing ismade. Compression means 69 and 71 do not tilt with the C-arm but are (asschematically shown in FIG. 3A) attached to the vertical standards 67and 68. These are fixedly attached to the non-rotating part of themammographic unit.

The compression plates can be moved in the horizontal plane to align thearea of interest (the lesion) with the axis of the X-ray beam. Themovement means are indicated at 76 and 79 and described in greaterdetail with FIG. 4.

In FIG. 4 the compression plates 69 and 71 are shown as attached to thestandard 67'. These compression plates are movably attached to thestandard so as to be able to compress the breast. On the side of thebreast opposite the source of the X-ray beam there is provided an imagereceptor means shown at 72. the image receptor means may be an X-rayfilm-screen or xerographic cassette or a fluorescent screen which may bepart of an imaging chain.

The image receptor of the X-ray is shown in a non-magnifying position,i.e. juxtaposed to the lower compression plate 71 in FIG. 3a. At 72' inthis figure there is shown an image receptor means which is removed fromthe lower compression plate and therefore provides magnification. Themagnification is the ratio of the distance of the X-ray beam source fromthe compressed breast as compared to the distance between the X-raysource and the image beam receptor means.

Needle holder insertion means are shown at 73. This needle holderinsertion means is shown as a means for inserting the needle holdernormal to the compression plates. After inserting the needle holder theC-arm is tilted, for example by 20 degrees, and another exposure is madeto determine whether or not the tip of the needle holder is sufficientlyclose to the center of the lesion. If it is sufficiently close, thehooked needle may be inserted through the needle holder and the needleholder may be withdrawn.

An alternative needle holder insertion means is shown in FIG. 3b at 74.This is an angled needle holder insertion means and is used when it isdesired to insert the needle holder at an angle--preferably 20 degreesto the normal. In this procedure the C-arm angle is reversed, afterpartial insertion of the needle holder, to minus 20 degrees to thenormal to check that the holder tip is sufficiently close to the lesion.

It should be understood that while an angle of 20 degrees is mentionedhere, this invention encompasses any angles less than 90 degrees thatprovide the ability to assure that the needle point is sufficientlyclose to the desired lesion.

In FIG. 4 the breast compression means is shown as assembly 70 includingupper and lower compression plates 69 and 71, respectively. The plate 69is moveably mounted to vertical standard 67' for movement by handle 85to compress the breast.

A horizontal plane movement means is shown and comprises a base plate 7lfixedly attached to pivot 66 or C-arm 61 for example.

Means such as handle and screw assembly 76 are provided for moving thecompression mechanism in the horizontal plane in the Y direction i.e.transverse to the C-arm by moving Y-shift mount 77 in the Y directionrelative to the base plate 75 with handle-screw arrangement 76.Similarly the compression assembly is moved in the horoizontal plane inthe X direction i.e. toward and away from the C-arm by moving theX-shift mount 78 relative to the mount 77 with handle/screw combination79. The horizontal adjustable movement mechanism expedites positioningthe lesion along the axis of the X-ray beam. X and Y shift scales 80aand 80b are provided in a preferred embodiment.

Means are provided to maximize the image quality with the minimum X-raydosage. More particularly as shown in FIG. 5 an X-ray beam source isprovided at 81. The source comprises an X-ray tube 82, an X-ray filter83 and an X-ray collimator 84. The X-ray tube is activated and energizedby a generator 86. The patient is shown at 87. X-ray receptor means 88are shown for receiving the X-rays after they pass through the patient.In the embodiment of the block diagram of FIG. 5 the receptor meanscomprises a fluorescent screen 89 optically coupled to an imageintensifier means 91 by optics indicated at 92. The output of the imageintensifier is coupled to a video camera 92. Coupling can be directcoupling or optical coupling which may include a distributor such asshown in FIG. 1. The optical coupler in FIG. 5 is shown at 93. A TVmonitor displays the image taken by the TV camera after processing whichincludes analog-to-digital conversion as indicated at 94. A framegrabber or frame store 96 is extremely helpful, especially in situationswhere the radiologist increments the dosage.

Incremental dosage may be provided by operating two controls. Forexample, an exposure time control 101 selects the exposure time whilethe other control 102 increments the dosage. The operation of theexposure time control 101 connects the generator 86 to the X-ray tube 82through a timing device 103. The timing device maintains the connectionbetween the generator and the tube for the set time indicated by thearrow 104 and then disconnects the generator from the X-ray tube. Whenonly the exposure time control 101 is operated, then the data acquireddue to the dosage provided during the set time of 104 is averaged in theframe store to provide the TV monitor with an image. However, if boththe exposure time control 101 and the dosage incremental control 102 areoperated, then another electronic switch 105 is operated to cause theoutput of the analog-to-digital converter to be transmitted to anaveraging unit 106. The averaging unit provides an average of aplurality of exposures, the averaged values are transmitted to the framestore to provide incrementally obtained average intensity data for theimage.

When only the image exposure time control 101 is operated then a NANDgate 107 opens to operate a switch means 108 to "dump" the incrementallyobtained average values by coupling the averaging unit contents toground.

When both controls 101 and 102 are operated, then the gate 107 isprevented from operating. The electronic switch 109 maintains a signalon the other input of NAND gate 107. Thus, the radiologist is able touse a minimum dosage every time. If he uses a sub-minimal dosage andobtains an unclear image, he can then increment that dosage until hedoes obtain a clear image. Alternatively, the incremental dosage meansmay be incorporated in a micro-computer used for system control. Itshould be noted that the incremental dosage means finds usage in generalX-ray systems and accordingly is not limited to mammographic biopsyneedle holder locating systems.

FIG. 6 indicates a system for obtaining a steroscopic image of thelesions within the breast. The steroscopic image is obtained by usingdual X-ray sources. In the system of FIG. 6 a pair of X-ray tubes areshown at 111 and 112. The tubes are grid-controlled so that one can beturned off while the other is providing X-rays. Thus, only one tubeprovides X-rays at a time. Alternatively a switching arrangement can beprovided to assure that only one tube is emitting X-rays at any giveninstant. An imaging chain 113 is shown. It includes fluorescent screen116, image intensifier 118, video camera 120, image processor 122, framegrabbers 124, and display mean 126 and 127.

The X-rays pass through the patient's breast shown at 131 in acompression unit made of plates 132a and 132b. In a preferred embodimenta one inch X-ray film screen is optically coupled to a one inch highresolution image intensifier. The image intensifier output is coupled toa high resolution TV camera. The stereo image thus acquired enables theradiologist to immediately judge the depth of penetration of the biopsyneedle holder from the two displays, while the breast is compressed.

Accordingly there is no need to release the breast with needles in itand recompress it in another direction. Similarly there is no need forrepositioning the X-ray tube to determine the depth of needle holderpenetration. Thus the improvement of FIG. 6 provides biopsy locatingneedle positioning which uses two X-ray sources along with the highintensity imaging equipment of FIGS. 1 and 2. The system can be appliedusing the folding mirror or prism described in conjunction with FIG. 2.

In operation the radiologist initially examines the preliminary X-rayfilms of the patient to determine the approximate region of the lesionin the breast. He then sets the patient in front of the breastcompression means. The breast is compressed using the breast compressionlocating movement and locating means to approximately locate the regionof interest of the breast along the axis of the X-ray beam so that thelesion is axial. An image is then acquired, either by film orfluoroscopically depending on whether a film or imaging chain X-rayreceptor is being used. Corrections are then made to accurately locatethe lesion in the axis of the X-ray beam. When this is done a needleholder is inserted. The needle holder insertion means of FIGS. 3a and 3bmay be used. When using the needle holder itself the needle holder isadjusted so that its axis is normal to the compression plates. Theneedle holder is inserted when there is a minimum shadow cast by theneedle holder. The needle holder is initially inserted into the breastfor a short distance. Subsequently the C-arm is tilted so that the beamis now displaced by about 20 degrees and the image is checked todetermine if the needle is sufficiently close to the lesion. Once thetip of the holder is sufficiently close to the lesion in the image,taken at a parallax angle, the needle is inserted through the holderuntil its tip lies within the lesion. At this time the needle holder isremoved. Thus the needle holder and the needle can be inserted using theequipment provided herein without having to uncompress and recompressthe breast. The time for locating the needle holder and inserting theneedle is reduced from 20-30 minutes to approximately 5-8 minutes. Whenthe imaging chain is used then it is important that a frame grabber isused to minimize the X-ray dosage. Thus one a sufficient increment ofdosages is supplied to obtain a good image, then the image is held bythe frame grabber and there is no necessity for continued dosage.

While the invention is described using specific embodiments it should beunderstood that these embodiments are described by way of example onlyand not as limitations on the scope of the invention.

What is claimed is:
 1. A mammographic biopsy needle holder positioningsystem for locating a needle holder in a breast to identify a lesiontherein that is to undergo biopsy, said system comprising:a biopsyneedle holder adapted to be inserted into the breast, x-ray tube meansfor generating x-ray beams, said x-ray tube means being positioned todirect said x-ray beams so that they pass through the breast of thepatient, breast compression means for compressing the breast to reducethe distance through the breast traversed by the x-ray beams, saidbreast compression means comprising first and second compression platesand means for moving said compression plates relative to each other tocompress said breast therebetween, x-ray receptor means for receivingx-rays, said x-ray receptor means being located opposite the x-ray tubemeans for receiving the x-ray beams after they have traversed the breastand for obtaining a view thereof, C-arm means for holding said x-raytube means and said x-ray receptor means aligned and spaced apart, arelatively immobile base means for supporting said breast compressionmeans, means for mounting said breast compression means to said basemeans while enabling said breast compression means to move laterally andtransversely on said base means relative to said C-arm means, and pivotmeans for mounting said C-arm means to said base means for supportingsaid C-arm means while enabling said C-arm means to pivot around saidbase means and said compression means for obtaining displays on saidreceptor means of different views of the biopsy needle holder insertedinto the breast in accordance with the angular position of said C-armmeans on said base means.
 2. The system of claim 1 wherein said X-rayreceptor means comprises film means for providing hard copy X-rayimages.
 3. The system of claim 1 wherein said X-ray receptor meanscomprises an imaging chain, said imaging chain comprising fluorescentscreen means for providing fluoroscopic images of the breast traversedby said X-ray beams, said fluorescent screen means being coupled to animage intensifier means for intensifying said fluoroscopic images, videocamera means coupled to the output of said image intensifier means forconverting said intensified fluoroscopic images to video signals, imageprocessing means for processing the video signals at output of saidvideo camera means to provide images, and display means for displayingthe images.
 4. The system of claim 3 wherein said image intensifiermeans is optically coupled to said video camera means, said opticalcoupling including image splitting means to enable on line opticallyviewing the output of said image intensifier and further processing theoutput of said image intensifier.
 5. The system of claim 1 wherein saiddifferent views comprise an initial view accomplished with the x-raytube mounted to provide x-ray beams at an angle of about 20° to thenormal to the compression plates, said needle holder being insertedcoaxially with said base, and a second view at a parallax angle atapproximately 20° from the first view.
 6. A mammographic biopsy needleholder positioning system for positioning a needle holder to locatelesions in a patient's breast, said system comprising:a biopsy needleholder adapted to be inserted into the breast, x-ray source means forgenerating x-ray beams directed to pass through the breast of thepatient, x-ray receptor means for receiving x-rays, said x-ray receptormeans being located opposite the x-ray source for receiving the x-raybeams after they have traversed the breast and for obtaining a viewthereof. compression means for compressing the breast substantially inthe direction of the x-ray beams, tilting means for tilting the x-raysource and receptor means for obtaining images of the breast atdifferent angles, said tilting means being constructed and arranged soas to tilt independently of said compression means but being attached tosaid compressing means, said compressing means including means formoving said compressing means, independently of said tilting means, in aplane traversed by x-ray beams from said x-ray source means, said x-rayreceptor means comprising an imaging chain including fluorescent screenmeans for providing a fluoroscopic image, image intensifier, meanscoupled to said fluorescent screen means for intensifying thefluoroscopic image of the fluorescent screen, means for coupling a videocamera to the output of said image intensifier means, means forprocessing the output of the video camera to obtain display data, meansfor providing a display from said display data, said processing meansincluding storage means for storing the display data used to provide thedisplay, means for incrementally energizing the x-ray source means,averaging means for averaging the averaging collected data obtainedresponsive to incrementally energizing the X-ray source means, means fortransmitting said averaged data from said averaging means to saidstorage means as display data, and means for terminating the incrementalenergization when the displayed image is of a required quality to viewthe biopsy needle holder inserted into the breast.